I don't know you and your car's history or where you are time wise in Full Maintenence, but I regularly get mine blades replaced by my dealership. Here's a quote with some info form an earlier post of mine:
"Per the "Caring for Your Vehicle" book that came with my '02, you should have your wiper blades replaced twice a year. From page 8, under Window Care, I quote "The wiper blades should be replaced twice a year, before and after the cold season. This is especialy important for vehicles with a rain sensor." Last fall my dealership replaced them no problem--maybe it's worth asking when in for service if your dealerships will do it for you."
Otherwise, I might order them from one of the dealerships who discount BMW parts if you want BMW blades. Good luck!
Anita